Piezoelectrically driven silicon microgrippers integrated with sidewall piezoresistive sensor

This paper presents the design, fabrication, and application of an piezoelectrically driven microgripper integrated sidewall piezoresistive force sensor for measuring the gripping force. Surface and bulk micromachining technology is employed to fabricate end-effectors and sensor of the microgripper from a single crystal silicon wafer. Vertical sidewall surface piezoresistor etching technique is used to form the side direction sensors. The end-effectors of the gripper are four-bar structures. Two fixed cantilever beams integrated with piezoresistive sensor are designed to sense the gripping force, and a piezoelectrically driven microactuator is designed to provide the force to operate the other two movable bars. The piezoelectrically driver adhered with the silicon end-effectors generates a linear horizontal motion 9 mum, which is amplified to 30 mum at the bar tip of the microgripper. Then the range of the operation is 25 mum - 140 mum. Testing results verify that the vertical sidewall surface piezoresistor etching technique is effective. The sensitivity of the piezoresistive sensors is better than 72 V/N, and the resolution is better than 3 muN.